1. Field of the Invention
The present invention relates to slide contacting members having slide contacting surfaces with a high abrasion resistance which are formed by hard plating and relates to production method therefor.
2. Description of the Prior Art
Conventionally, the hard plating has been utilized in order to improve the abrasion resistance of slide contacting surfaces of slide contacting members such as cylinder liners of a combustion engine for automobile by forming hard plated layers on the slide contacting surfaces. Usually, these slide contacting members are used in a state lubricated by oil. In order to improve the abrasion resistance of slide contacting surfaces, in other words, to reduce the wear of mating counter members which are slide contacted to the slide contacting members under a high contact pressure, there has been proposed a method for improving the holding property of oil and/or the diffusibility of oil by forming a lot of small concavities dispersed on the surface of the slide contacting member (See, for example, Japanese patent publication No. 25841/1986.).
As the method for forming small concavities, there have been proposed the porous plating with use of the reversed electrolytic process, a forming method of concavities by plating surfaces of parent material after making gouges on the surfaces mechanically and/or a method for forming concavities on plated surfaces utilizing the photo-etching process (See, for example, Japanese patent laid open publication No. 3431/1985).
FIGS. 6(a) and 6(b), show concavities 3 schematically which are formed on a hard layer 2 plated on a parent material 1 with use of said reversed electrolytic process and photo-etching process, respectively.
The slide contacting member having concavities 3 formed according to such conventional processes as mentioned above has an essential defect in that the edge portion 3a of each concavity 3 formed is liable to become acute. This causes scratches on a surface of a counter member 4 being slide contacted thereto coupled with the high hardness of the plated layer 2 and, due to these scratches, the abrasion resistance of the counter member 4 is lowered considerably.
In order to solve this problem, there has been proposed a method for forming edge portions of concavities round by repeating the photo-etching process twice.
However, this method is too time-consuming because of complicated treatments therefor.